Lunar eclipses occur when the moon enters Earth's shadow. In this case, the moon is entering the very edge of that shadow instead of running right through the heart of it, which is why the eclipse will be so fleeting.

NASA has prepared a map showing where the eclipse will be visible. In the United States, the total eclipse will be observable from the West Coast to the U3 line (which runs roughly along the Mississippi River), while a partial lunar eclipse will be visible east of that line, with sunrise cutting the event short:

The eclipse will begin at 3:16 a.m. PT when the shadow of the earth begins to cover the moon. Totality will begin at 4:58 a.m. PT, with the greatest eclipse at 5 a.m. and totality ending at 5:03 a.m. The remaining partial eclipse will last until 6:45 a.m. PT, according to NASA.

Because the moon can look red during an eclipse, the event is sometimes called a "blood moon."

This eclipse is the third in a tetrad, or a period of four eclipses, which began on April 15, 2014. The next and final lunar eclipse in the cycle will be on Sept. 28.

Related on HuffPost:

Lunar Eclipse

Lunar Eclipse

1

of

80

Lunar Eclipse, April 15, 2014

The moon moves out of a lunar eclipse over southern California as seen from Korea town, west of downtown Los Angeles early on April 15, 2014. The entire event was to be visible from North and South America, but sky watchers in northern and and eastern Europe, eastern Africa, the Middle East and Central Asia were out of luck, according to NASA. AFP PHOTO/JOE KLAMAR (Photo credit should read JOE KLAMAR/AFP/Getty Images)